Muscles and animal movement

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Muscles and animal movement
Chapter 5

• Structure and Function

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Means of animal movement

• Effects of
• Inertia and momentum
• Viscosity of medium
• Microtubules
• Intracellular
• Cilia
• Flagellae
• Muscles

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Microtubules

• Tubelike polymers of the protein tubulin
• Highly conserved
• Multiple isoforms
• Anchored at both ends
• Microtubule-organization center (MTOC) () near
  the nucleus
• Attached to integral proteins () in the plasma
  membrane

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Movement of pigment granules
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Microtubule Assembly
Figure 5.4
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Vesicle Traffic in a Neuron
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Cilia and Flagella
Figure 5.8
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Microtubules and Physiology
Table 5.1
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Microfilament Structure and Growth (Actin)
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Isolated actin filaments
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Actin Networks
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Actin and Myosin Function
Table 5.2
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Muscle types

• Skeletal muscle
• Striated
• Voluntary
• Smooth muscle
• Non-striated
• Involuntary
• Cardiac muscle
• Electrically coupled cells
• Molluscan Catch muscle
• Insect flight muscle

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Skeletal Muscle

• Many animals contain over 400 skeletal muscles
• 40-50 of total body weight
• Functions of skeletal muscle
• Locomotion and breathing
• Postural support
• Heat production

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Structure of Skeletal MuscleConnective Tissue
Covering

• Epimysium
• Surrounds entire muscle
• Perimysium
• Surrounds bundles of muscle fibers (fascicles)
• Endomysium
• Surrounds individual muscle fibers

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Structure of Skeletal MuscleMicrostructure

• Sarcolemma
• Muscle cell membrane
• Myofibrils
• Threadlike strands within muscle fibers
• Actin (thin filament)
• Troponin
• Tropomyosin
• Myosin (thick filament)
• Z-line
• a-actinin

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Structure of Skeletal Muscle The Sarcomere

• Further divisions of myofibrils
• Z-line
• A-band
• I-band
• Within the sarcoplasm
• Sarcoplasmic reticulum
• Storage sites for calcium
• Transverse tubules
• Terminal cisternae

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Thick and Thin Filaments
Figure 5.15
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Myosin
Figure 5.12
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Insect flight muscle
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Three-Dimensional Structure of Sarcomere
Figure 5.18
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Cross bridges
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Muscular Contraction

• The sliding filament model
• Muscle shortening occurs due to the movement of
  the actin filament over the myosin filament
• Formation of cross-bridges between actin and
  myosin filaments
• Reduction in the distance between Z-lines of the
  sarcomere

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The sliding filament model

• Actin
• Myosin
• Actinin (z-disc)

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Length/tension relationship for a vertebrate
sarcomere
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Length/tension relationship for a whole muscle
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Sliding Filament Model
Figure 5.13
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Generation of force by myosin and actin
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Troponin and Tropomyosin
Figure 5.21
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Regulation of muscle contraction
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Regulation of Contraction by Ca2
Figure 5.22
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Calcium and ATP required for force
generation Force proportional to calcium
concentration
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Calcium drives ATPase activity of myosin
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Contraction occurs in presence of ATP and
calcium Relaxation occurs only in presence of ATP
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• Summary of ionic events in muscle contraction